With the advent of tuned loop antennas as a convenient antenna structure for reduced operational space requirements, there is a need for a broadband loop antenna which does not require tuning and yields near 100% efficiency. With conventional tuned loop structures, one to three dB of antenna gain may be lost due to inherent losses of the LC networks operating at high current levels as a result of high Q. This results in narrow operational bandwidths.
The present invention relates to single wire full wavelength loop antennas which are usually fed at a high impedance and which exhibit a narrow bandwidth. A full wave open stub coaxial loop provides maximum efficiency and maximum bandwidth at a convenient inherent 50 ohm feed impedance. The electrical length of the coaxial loop is greater than 1.4 wavelengths.